Aircraft need to produce varying levels of lift for take-off, landing and cruise. A combination of wing leading and trailing edge devices are used to control the wing coefficient of lift. The leading edge device is known as a slat whereas the trailing edge device is known as a flap. On larger aircraft there may be several flaps spaced along the trailing wing edge. During normal flight the flaps are retracted under the trailing edge of the wing. However, during take-off and landing they are deployed rearwardly of the wing so as to vary the airflow across and under the wing surfaces to reduce the speed of the aircraft and control the angle of descent. The flaps usually follow an arcuate or curved path between their stowed and deployed positions. By varying the extent to which the flap is deployed along said path, the lift provided by the wing can be controlled.
An assembly is required to support and guide movement of a flap between stowed and deployed positions and a typical arrangement of a swinging track flap support assembly commonly used on larger aircraft is shown in the isometric view of FIG. 1. A swinging track design is required for larger aircraft, as the flaps must be able to follow a constantly changing three-dimensional path to allow for extension that is widthwise and perpendicular to the direction of air flow across the wing at its fully deployed position.
With reference to FIG. 1, there is shown a mid rear spar 1 of an aircraft wing and aileron closing ribs fore and aft 2, 3. A bracket hinge 4 is attached to the fore aileron closing rib 2 and a swinging arm 5 is connected to the bracket hinge 4 for rotation about a fail-safe pin 6. The swinging arm 5 has an arcuate guide track 7 and a roller carriage (not shown) is mounted to the swinging arm 5 for movement along the guide track 7. The roller carriage is connected to a flap via a bearing 9 and a flap rib 8, the flap being directly mounted to the flap rib 8.
As the flap rib 8 is extended, the roller carriage moves along the guide track 7. Sideways or lateral movement of the flap rib 8 in a direction along the length of the wing causes the arm 5 to pivot about pin 6. The combination of the bearing 9 and swinging arm 5 allows the flap rib 8 to be supported along its required path and throughout its entire range of movement without jamming.
It will be appreciated that space for components within the wing structure close to the trailing edge of an aircraft wing is very limited. The requirement to house a number of different components and fuel tanks places considerable design restrictions on the shape of the wing in addition to increasing weight, manufacturing costs and complexities.
It is therefore desirable to provide a light and robust support assembly that takes up a minimum amount of space within the wing structure but which still provides support throughout the entire range of movement of a wing trailing or leading edge device.